Any use for Nightmare IVr6 for study purposes or due to distribution rights and/or similarity to DS no need for that?

I won't be distributing Nightmare IV because Descartes expressly revokedsuch license from everyone. You could argue for years whether this revocation can be upheld, the nature of its legal force, if any, etc. Butthe short answer is no, I won't be making it available for download.

On the other hand, the Dead Souls 1 ( http://lpmuds.net/downloads.html#ds1 )lib is almost exactly the same thing as the Nightmare IV lib. For thepurposes of code analysis, you'd gain nothing from using NMIV over DSI.